Bottlenose skate | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Order: | Rajiformes |
Family: | Rajidae |
Genus: | Rostroraja |
Species: | R. alba |
Binomial name | |
Rostroraja alba (Lacépède, 1803) | |
Synonyms | |
Raja albaLacepède, 1803 Contents |
The bottlenose skate, spearnose skate, or white skate (Rostroraja alba) is a species of skate in the family Rajidae. It is a benthic fish native to the coastal eastern Atlantic Ocean. Due to overfishing, it has been depleted or extirpated in many parts of its former range in the northeastern Atlantic and the Mediterranean Sea, and is now endangered.
The bottlenose skate is found along the coastlines of the eastern Atlantic Ocean, from the southern British Isles to South Africa and extends into the southwestern Indian Ocean to Mozambique. It is present as well in the western and northeastern sectors of the Mediterranean Sea. [2] It is a benthic species of sandy and detrital bottoms, at depths of 40–400 m (exceptionally down to 500 m) from coastal regions to the upper continental slope. Du Buit (1974) reported that it is more prevalent in rocky habitats. [1]
Most bottlenose skates are 60–150 cm (24–59 in) long, [1] with maximum recorded lengths of 230 cm (91 in) for males and 202 cm (80 in) for females. [3] The flattened, angular pectoral fin fisc is about 1.4–1.5 times as broad as long. The snout is broad-based, abruptly tapering to a protruding sharp point and covered with small, sharp thorns. There are 40–45 rows of teeth in the upper jaw. The juveniles have 1 thorn before and 0–1 thorns behind the eyes and three rows of large thorns on the tail, 10–16 on the midline and 7–17 on either side. The adults have about 6 thorns around the inner margin of the orbit and 16–30 mid-dorsal and 17–29 lateral thorns on the tail. The skin is rough in adults except for a smooth patch in the center of the disc; the underside is prickly except for smooth patches on the snout. The young are entirely smooth, except for on the snout. Large juveniles and adults are greyish or bluish with or without numerous small white spots above, white below with brown to black disc margins. Hatchlings are plain reddish-brown above, often with blue spots, and white below with broad dusky disc margins. [3] [4] [5]
The bottlenose skate is a benthic predator of bony fishes, other elasmobranchs, fish offal, crabs, shrimps, mysids, octopus, and cuttlefish. Younger, smaller fish are usually found in shallower water. Like other skates, this species is oviparous, with females producing 55–156 ova per year after a gestation period of 15 months. The egg cases are oblong in shape, with stiff pointed horns at each corners and the larger horns flattened. They are deposited in sandy or muddy flats in the spring. The capsules measure 12.5–18.3 cm (4.9–7.2 in) long and 10–13.9 cm (3.9–5.5 in) wide. [3] [5] This species is estimated to mature at 130 cm (51 in) for males and 120 cm (47 in) for females. [1]
In the 17th century, the bottlenose skate was prized by the French for food. [5] Because of its large size and slow reproductive rate, the bottlenose skate is extremely vulnerable to exploitation by fisheries. Anecdotal data suggests that there has been a substantial decline in the abundance and geographical range of this species in the north Atlantic and Mediterranean. In the north Atlantic, populations of bottlenose skates have declined severely or disappeared from the Bay of Biscay and the Irish Sea; there are no longer targeted fisheries in these regions due to localized population collapses in the 1960s. There are also no recent records of this species in the waters off the United Kingdom, where it historically occurred. The bottlenose ray still persists along the coast of the Iberian Peninsula, though the population data is uncertain due to confusion with the shagreen ray (Leucoraja fullonica) and the sandy ray (L. circularis). [1]
In the Mediterranean, bottlenose skates of most size classes down to egg cases are taken as by-catch in multi-species trawling fisheries. Historically, it was caught frequently off the coasts of Tunisia and Morocco in the 1970s and was described as more or less frequent in the northwestern Mediterranean from the 1950s to the 1970s. The MEDITS trawl surveys, begun in 1985 and carried out six times a year in four geographic regions, indicates that the bottlenose skate is now very rare in the Mediterranean and that it has been reduced to a small fraction of its former range. The Italian National Group for Demersal Resource Evaluation (GRUND) survey captured this species infrequently in the Adriatic Sea. The species is assessed globally as Endangered in the IUCN Red List, and Critically Endangered in the northeast Atlantic. [6] However, its status will require re-evaluation once data from its African range is available. [1] In 2010, Greenpeace International added the bottlenose skate to its Seafood Red List, which includes commonly marketed species that "have a very high risk of being sourced from unsustainable fisheries". [7]
The school shark is a houndshark of the family Triakidae, and the only member of the genus Galeorhinus. Common names also include tope, tope shark, snapper shark, and soupfin shark. It is found worldwide in temperate seas at depths down to about 800 m (2,600 ft). It can grow to nearly 2 m long. It feeds both in midwater and near the seabed, and its reproduction is ovoviviparous. This shark is caught in fisheries for its flesh, its fins, and its liver, which has a very high vitamin A content. The IUCN has classified this species as critically endangered in its Red List of Threatened Species.
Squatina squatina, the angelshark or monkfish, is a species of shark in the family Squatinidae, that were once widespread in the coastal waters of the northeastern Atlantic Ocean. Well-adapted for camouflaging itself on the sea floor, the angelshark has a flattened form with enlarged pectoral and pelvic fins, giving it a superficial resemblance to a ray. This species can be identified by its broad and stout body, conical barbels, thornless back, and grayish or brownish dorsal coloration with a pattern of numerous small light and dark markings. It measures up to 2.4 m (7.9 ft) long.
The common sole, Dover sole, or black sole is a species of flatfish in the family Soleidae. It is one of the largest fish in the Solea genus. It lives on the sandy or muddy seabed of the northern Atlantic and the Mediterranean Sea where it often partially immerses itself in the substrate. The upper side is greyish-brown while the underside is white. It grows to a maximum length of about 70 cm (28 in). The species is prized as a food fish, being caught mostly by trawling on the seabed.
The barndoor skate is a species of marine cartilaginous fish in the skate family Rajidae of the order Rajiformes. It is native to the northwestern Atlantic Ocean, and is found from the Grand Banks of Newfoundland and the southern side of the Gulf of St. Lawrence south to North Carolina. The fish is one of the largest skates found in the North Atlantic Ocean, reaching lengths up to 1.5 m (5 ft). It is carnivorous, feeding on invertebrates and other fish found near the sea floor.
The blue skate, also known as the grey skate or blue-grey skate, is a species of cartilaginous fish, a ray, belonging to the family Rajidae, the skates. It was formerly considered to be conspecific with the flapper skate, the combined taxon being known as the common skate. Historically, it was one of the most abundant skates in the northeast Atlantic Ocean and the Mediterranean Sea. Despite its name, today it appears to be absent from much of this range. Where previously abundant, fisheries directly targeted this skate and elsewhere it is caught incidentally as bycatch. The former species was uplisted to critically endangered on the IUCN Red List in 2006 and it is protected within the EU.
The spotback skate is a species of fish in the family Arhynchobatidae. It is found off the Atlantic coasts of Argentina, Brazil, and Uruguay where its natural habitat is over the continental shelf in the open sea. It is a large fish, growing to over a metre in length. It feeds mainly on other fish according to availability, with shrimps, octopuses and other invertebrates also being eaten. Reproduction takes place throughout most of the year, with the eggs being laid in capsules that adhere to the seabed. The spotback skate is the subject of a fishery and is thought to be overfished, resulting in Greenpeace adding the fish to its red list of fish to be avoided, and the International Union for Conservation of Nature listing it as an "endangered species".
The big skate is the largest species of skate in the waters off North America. They are found along the Pacific Coast from Alaska to Baja California, typically from the intertidal zone to a depth of 120 m (390 ft), and feed on benthic invertebrates and small fishes. They are unusual among skates in that their egg cases may contain up to seven eggs each. This species is one of the most commercially important skates off California and is sold for food.
The Gulf torpedo or variable electric ray, is a species of electric ray in the family Torpedinidae. It is found in the Indian Ocean, but may represent a species flock of several local endemic species. It is distinguishable from other Torpedo species in its range by its ornate dorsal coloration. Another common name, marbled electric ray, is not to be confused with Torpedo marmorata.
The undulate ray is a species of skate and cartilaginous fish found in the Mediterranean and East Atlantic from southern Ireland and England to the Gulf of Guinea. It is found in areas with mud or sand, and may occur as deep as 200 m (660 ft), though it prefers shallower depths. It is considered endangered due to overfishing.
The shagreen ray, also known as shagreen skate or fuller's ray, is a species of skate in the family Rajidae. This ray is found in the eastern Atlantic Ocean, from Murmansk, Russia through Norway, southern Iceland, the Faroe Islands, the Celtic Sea, the northern North Sea and Skagerrak, to western Morocco and the Madeira archipelago, but not in the shallow waters off England and Wales. It is also recorded sporadically in the Mediterranean Sea.
The common stingray is a species of stingray in the family Dasyatidae, found in the northeastern Atlantic Ocean and the Mediterranean and Black Seas. It typically inhabits sandy or muddy habitats in coastal waters shallower than 60 m (200 ft), often burying itself in sediment. Usually measuring 45 cm (18 in) across, the common stingray has a diamond-shaped pectoral fin disc slightly wider than long, and a whip-like tail with upper and lower fin folds. It can be identified by its plain coloration and mostly smooth skin, except for a row of tubercles along the midline of the back in the largest individuals.
The spiny butterfly ray or giant butterfly ray is a species of butterfly ray, family Gymnuridae, native to the shallow coastal waters of the Atlantic Ocean. A large ray that can measure over 2 m across, it may be distinguished from the sympatric smooth butterfly ray by the spine at the base of its tail and by a small tentacular structure on the margin of each spiracle. Slow-reproducing and valued for its meat, in recent decades its population has experienced a decline of over 30%, and it has become Critically Endangered in certain parts of its range.
The mangrove whipray or whitetail stingray, is a species of stingray in the family Dasyatidae. It is widely distributed in the Indo-Pacific region from the Red Sea to northern Australia and Micronesia. A benthic inhabitant of shallow inshore waters, juvenile mangrove whiprays favor mangrove and estuarine habitats, while adults favor sandy to rocky areas in lagoons and coral reefs. This species can be identified by its thick, oval pectoral fin disc that is dark gray above with numerous white flecks, and by its relatively short, whip-like tail that is white past the stinging spine. It grows up to 1.4 m (4.6 ft) across.
The common guitarfish is a species of cartilaginous fish in the family Rhinobatidae. It is native to the eastern Atlantic Ocean and the Mediterranean Sea. It is a bottom-dwelling fish feeding on crustaceans, other invertebrates and fish. The females give birth to live young. Its lifestyle makes it vulnerable to trawling and other fishing methods, populations seem to be declining and it has disappeared from parts of its range.
The clearnose skate is a species of cartilaginous fish in the family Rajidae. R. eglanteria is also known by other common names such as the brier skate and summer skate. Clearnose skates are easily identified by the translucent patches on either side of their snouts and their mottled dorsal surface. They are found along the Atlantic and Gulf coasts of the United States in shallow waters of the continental shelf.
The pita skate is a medium-sized skate in the family Rajidae. The holotype and only known specimen was found in the northern Persian Gulf, in Iraqi waters. It was collected at a depth of less than 15 m (49 ft).
The blackchin guitarfish is a species of cartilaginous fish in the family Rhinobatidae. It is native to the eastern Atlantic Ocean and the Mediterranean Sea. It is a bottom-dwelling fish feeding on crustaceans, other invertebrates and fish. The females give birth to live young. Its lifestyle makes it vulnerable to trawling and other fishing methods, populations seem to be declining and it is subject to intensive fishing pressure, with its fins being sold into the Asian market. The International Union for Conservation of Nature has assessed its conservation status as being "critically endangered".
The thickback sole, also known as the bastard sole and lucky sole, is a species of flatfish from the family of true soles, the Soleidae. It is found in the eastern Atlantic Ocean and the Mediterranean Sea, it is a quarry for fisheries in the Mediterranean.
Synchiropus phaeton or the Phaeton dragonet is a species of bony fish of the family Callionymidae, the dragonets. It can be found in the Mediterranean and in the eastern Atlantic.
The rough ray is a Mediterranean ray species of the Rajidae family described by Delaroche in 1809.